Hydraulic rolling mills



E. M. SCOTT HYDRAULICv ROLLING MILLS Jan. 9, 1968 2 Sheets-Sheet 1 Filed April 21, 1964 INVENTOR Earle M. Scott Jan. 9, 1968 -E. M. SCOTT 3, 4

HYDRAULIC ROLLING MILLS Filed April 21, 1964 1 2 Sheets-Sheet 2 Fig.3.

INVENTOR EarleM. Scott United States Patent 3,362,204 HYDRAULIC ROLLING MILLS Earle M. Scott, Mount Lebanon Township, Allegheny County, Pa, assignor to Pittsburgh Steel Foundry & Machine Company, Textron Incorporated, a corporation of Rhode Island Filed Apr. 21, 1964. Ser. No. 361,403 3 Clm'ms. (Cl. 72-245) This invention relates to rolling mills in which metal strip is reduced to a thinner gauge. The invention is particularly useful in the precision reduction of very thin strip in which the roll pressure may optionally be hydraulically controlled.

The rolling of metal strip to desired gauge is well known and is highly developed. The metal is customarily rolled hot in the first instance from ingot form. Thereafter the strip is usually cold reduced to desired igauge. In the rolling of thin gauges, control of the gauge becomes more critical than with heavy gauges, since small variations in strip gauge may constitute a large percentage of the strip thickness In the usual rolling mill, a pair of housings are set on foundations on opposite sides of the strip pass line. The housings customarily are heavy castings which are in the form of upright rectangular structures. The housing ordinarily comprises a base section, two upright sections, and an upper section, the Whole being an integral memher or assembly of members. The open area between the upper and lower sections and the two upright sections is known as a window and receives the necks of the rolls which are journaled in bearings positioned in the window. Thus the rolls extend between the two housings and the strip passes between the working rolls. In four-high mills, which are customarily used for cold reduction, back-up rolls are used which carry the load of rolling. Ordinarily the bearing for the lower back-up roll of a four-high mill is in fixed position and the bearing of the upper roll is vertically adjusted by a screw-down mounted on the housing. In this manner the clearance between the back-up rolls, and, necessarily, between the work rolls, is controlled by the screw-downs. When the gap is initially adjusted and the mill then takes a bite on the strip, the strip is compressed and reduced between the rolls. At the same time it exerts an opposite force on the rolls tending to force them apart. The force of the strip strains the screw-downs and the housings which hold the rolls in position. The screw-downs are compressed and the side members of the housings are elongated. There are, of course, bending strains in the upper and lower sections of the housings and complex strains in the rolls, but those strains are of relatively minor magnitude compared to the strains in the vertical sections of the housings. Although the gauge of the mill may be properly adjusted at the time the end of the strip is fed in, the rolls spread apart as soon as they take a bite on the strip, thereby causing an increased gauge to be rolled until the screw-downs can be further adjusted to bring the rolls to proper gauge while rolling continues. The problem is complex in that the ends of strip are ordinarily non-uniform with respect to the center sections. The condition is repeated each time the rolling process is repeated, so that the end irregularities tend to become aggravated.

It has been proposed to employ hydraulic pressure to adjust the force on the rolls so that a constant rollin-g force is maintained. If the metal being rolled is substantially uniform, the application of a constant force should produce strip of uniform gauge. That scheme does not avoid the problems inherent in coming to steady state when the initial bite is taken on the strip. It has also been proposed to pre-strain the housing by bringing about pressure between the rolls-either by hydraulic pressure Patented Jan. 9, 1968 or by screw-down adjustmentprior to the time the strip is fed to the mill. These proposals have not been entirely satisfactory in practice. Many transient problems exist which require that adjustments be made during actual rollmg.

I have invented new and useful improvements in rolling strip which overcome disadvantages of the prior art and make possible the more accurate, precise, and convenient rolling of metal strip with less waste and reject material.

I provide a pair of opposed housings having a window to receive the ends of rolls extending between the housing. I further provide a lower roll chock slidably positioned within each window, yielding means extending between the lower roll chock and the bottom of the housing and yieldingly urging the lower roll chock upwardly. I further provide rigid means extending between the lower roll chock and the top of the window, and an upper chock slidably positioned within the window intermediate the lower roll chock and the top of the window. I further prefer to provide rigid means extending between the upper roll chock and the top of the window. I preferably provide fluid pressure means intermediate the bottom of the housing and the lower chock and means to supply fluid under pressure thereto. I preferably provide mechanical screw-down means intermediate the upper roll chock and the top of the housing. Where desirable, I mount the necks of back-up rolls within the chocks and position work rolls intermediate the back-up rolls.

I further provide constant pressure fluid supply means by which fluid is supplied to the fluid pressure means at a constant and predetermined fluid pressure. I prefer to provide means to adjust said fluid pressure whereby any desired fluid pressure can continuously be maintained in said fluid pressure means. I preferably provide pressure pump means delivering fluid into a fluid circuit and relief valve means allowing fluid to escape from the fluid circuit whenever the pressure within the circuit exceeds a preset value.

Other details, objects, and advantages of my invention will become apparent as the following description of a present preferred embodiment thereof proceeds. In the accompanying drawings I have illustrated a present preferred embodiment of my invention in which FIGURE 1 is a side view of a four-high rolling mill embodying the invention.

FIGURE 2 is an end view of a portion of the mill shown in FIGURE 1 with some parts in section and taken along line II-II of FIGURE 1.

FIGURE 3 is a sectional View taken along line III-III of FIGURE 1; and

FIGURE 4 is a schematic diagram of the hydraulic circuit and associated parts of the mill. The mill comprises a pair of spaced-apart housings 1 and 2 (FIGURES 1 and 2). The strip being rolled passes through the mill between the housings along a strip pass line 3. The strip passes between an upper work roll 4 and a lower work roll 5. Work rolls 4 and 5 are backed up by an upper back-up roll 6 and a lower back-up roll 7.

Each housing is mounted upon shoe plates 8, which are unitary with the mill foundation. Separators 9 maintain the two housings in correct spaced apart relationship. Each housing has a rectangular window 10 within which the roll necks are journaled. Guide plates 11 are bolted to the housing and project slightly beyond the edge of the window. They engage slots (which are not shown) in bottom back-up roll chock 12, permitting chock 12 to move up and down in window It) in a vertical direction, but restraining it in conventional manner against horizontal movement. Chock 12 has upwardly extending abutments 13 which extend upwardly adjacent the vertical walls of window 10. Abutments 13 form a centrally lo- 3 cated recess 14. Recess 14 receives bottom work roll crock 15, in which bottom work roll is journaled. Posts 16 and 17 which are channel shaped in plan (FIGURE 3) are fitted in the edge of window 10. Their edges wrap around a portion of upright sections 13 and 19 of each housing which define the sides of window 10. Each of posts 16 and 17 is vertically slidably p0si.ioned relative to the housing and is held in position by bolts 20, which permit vertical sliding movement of each post relative to the housing. Guide plates 21 are connected to posts 16 and 17 by bolts which have been omitted from the drawings for clarity. The guide plates fit within vertical slots 22 formed in upper back-up roll chock 23. Upper backup roll chock 23 is thereby free to move up and down vertically relative to posts 16 and 17, as well as to the housing, but is restrained against horizontal movement.

The top of posts 16 and 17 abut against the housing at the top of window in sockets 24 and 25, respectively, formed in the top section of the housing.

Upper back-up roll chock 23 is moved up and down by a screw-down mechanism 26 intermediate the chock and the top of the window. Screw-down mechanism 26 is driven by a motor 27 through a gear reducer 28 in conventional fashion.

A pad 29 is positioned upon the bottom surface of each bottom back-up roll chock. It bears against a pad 30 resting upon a piston 31. Each piston 31 is slidably positioned within a hydraulic cylinder 32 which rests upon the bottom section of the housing at the bottom of window 10. A load bearing ring 33 is fitted to the bottom of each piston 31 to support the piston upon the bottom of the cylinder when it is not forced upwardly by hydraulic pressure. Packing rings 34 seal the piston to the cylinder walls to retain fluid under pressure within the cylinder. An air vent 35 is provided to permit air to be released from each cylinder. An inlet 36 is formed at the bottom of each cylinder for admission of a hydraulic fluid, such as oil, under pressure. Shrouds 37 are provided upon the cylinders and pistons to prevent dirt from becoming trapped between the walls of the cylinder and the pistons.

The hydraulic system is schematically illustrated in FIGURE 4. It comprises a sump 38 containing a supply of oil. A high pressure pump 39 driven by electric motor 40 is connected to the sump on its suction side. It pumps oil through check valves 41 into high pressure oil lines 42 which are connected by branch connections 43 to inlets 36 in pistons 31.

Relief valves 44 are connected to high pressure lines 42. Valves 44 discharge to a manifold 45 which is in turn connected to a master relief valve 46. Valve 46 discharges through a line 47 to sump 38. Pressure in each of the cylinders 32 may be independently controlled by adjustment of the corresponding relief valves 44, or a like pressure may be maintained in both cylinders 32 by setting valves 44 to relieve the pressure and making all adjustments at relief valve 46. Discharge lines 48 connect a drain valve 49 to high pressure lines 42. Valve 49 is operable to a closed and to an open position in which it opens high pressure lines 42 to sump 38.

A pressure gauge 50 is connected to each high pressure line 42 through a snubber 51 and a shut-off valve 52.

The mill may be operated in the conventional manner by stopping hydraulic pump 39 and opening relief valves 44 and 46, and releasing all of the pressure within the cylinders 32. Pistons 31 will then settle in the cylinders until bearing ring 33 comes to rest upon the bottom of the cylinder. Thereafter the rolling pressure and reduction in gauge are controlled by the screw-down in the conventional manner.

The mill may also be operated by supplying oil under pressure to cylinders 32. When hydraulic pressure is applied, pistons 31 force bottom back-up roll chocks 12 upwardly. Abutments 13 are likewise urged in an upward direction against posts 16 and 17. The upper ends of posts 16 and 17 are restrained from upward movement by the top of the housing. When the hydraulic force is applied, therefore, a compressive force is exerted upon posts 16 and 17. They exert an equal force upon the housing in which the side members are in tension. It is of course to be noted that the force straining the housing is the sum of the forces straining posts 16 and 17. A downward force is applied at the bottom of window 10 by the opposite reaction of cylinder 32. The outward forces strain the housing in tension, elongating vertical sections 18 and 19. The relief valves are set to maintain constant and sufficiently high hydraulic pressure. Screw-downs 26 are adjusted to the proper position for rolling and the strip is fed between the rolls which are driven in the conventional manner. The strip tends to force the rolls apart and a force is transmitted upwardly through screw-downs 26 and downwardly through the lower work roll chocks and hydraulic cylinders. As that force is applied, the forces transmitted through posts 16 and 17 are, pro tanto, reduced. Since the upward force produced by the hydraulic cylinders 32 is solely a function of the fluid pressure and remains com stant, the opposing forces must always equal the upward force. Accordingly, the downward forces of the lower rolls and of posts 16 and 17 must always equal the upward force of piston 31. In order for there to be equilibrium, there must be equal upward forces exerted by posts 16 and 17 and screw-downs 26. In this manner the forces applied at the top and bottom of each housing and theextent to which it is strained remain constant despite wide varia tions in the rolling forces. Even though there are substantial and almost instantaneous changes in the forces tending to separate the rolls, the force applied to each housing remains constant and unchanged. In this man-' ner, strip, notably thin foils and the like, can readily be rolled with extreme precision and with less waste than has heretofore been possible.

While I have illustrated and described a present preferred embodiment of my invention, it is to be understood that I do not limit myself thereto, and that my invention may be otherwise variously practiced within the scope of the following claims.

I claim:

1. A rolling mill comprising a pair of opposed hous ings, each of said housings having a window to receive the ends of rolls extending therebetween, a lower roll chock slidably positioned within the window, yielding means extending between the lower roll chock and the bottom of the window and yieldingly urging the lower chocks upwardly, rigid means extending in load truns mitting relationship between the lower chock and the top of the window, an upper roll chock slidably positioned within the window intermediate the lower roll chock and the top of the window, rigid means extending be tween the upper roll chock and the top of the window, and upper roll means and lower roll means extending between the upper roll chocks and lower roll chocks respectively in said housings.

2. A rolling mill comprising a pair of opposed housings, each of said housings having a window to receive the ends of rolls extending therebetween, a lower roll chock slidably positioned in the window, fluid pressure means extending between the bottom of the housing and the lower roll chock, fluid supply means in connection with said fluid pressure means and adapted to supply fluid under a controlled pressure to said fluid pressure means, rigid means extending in load transmitting relationship between the lower roll chock and the housing adjacent the top of the window, an upper roll chock positioned in the window intermediate the lower roll chock and the top of the window in non-yielding relationship to the top of the window, and upper roll means and lower roll extending between the two housings and journaled in the upper roll chocks and the lower roll chocks respectively.

3. A rolling mill comprising a pair of opposed housings, each said housing having a window, upper roll means and lower roll means disposed in vertical relationship and extending between the housings, lower roll chock means slidably disposed in the windows for vertical movement therein, vertically extensible hydraulic cylinder means intermediate the housing-S adjacent the bottoms of the windows and the lower roll chock means, hydraulic fluid supply means in operative connection with said hydraulic cylinder means, and adapted to deliver a controlled pressure to the hydraulic cylinder means, upper roll chock means slidably disposed in the windows intermediate the lower roll chock means and the tops of the windows for vertical movement in the windows, the upper roll means and the lower roll means being journaled in the upper roll chock means and the lower roll chock means respectively, screw-down means in operative enof the housings whereby the upper roll chock means are maintained in non-yielding relationship to the tops of the windows, and non-yielding load transfer means extending in load transmitting relationship between the lower roll chock means and the housings adjacent the tops of the windows.

References Cited UNITED STATES PATENTS 3,024,679 3/ 1962 Fox 72-243 3,124,982 3/ 1964 Neumann 72-240 3,247,697 4/1966 Cozzo 72--243 RICHARD J. HERBST, Primaly Examiner.

gagement with the upper roll chock means and the tops 15 A. RUDERMAN, Assistant Examiner. 

1. A ROLLING MILL COMPRISING A PAIR OF OPPOSED HOUSINGS, EACH OF SAID HOUSINGS HAVING A WINDOW TO RECEIVE THE ENDS OF ROLLS EXTENDING THEREBETWEEN, A LOWER ROLL CHOCK SLIDABLY POSITIONED WITHIN THE WINDOW, YIELDING MEANS EXTENDING BETWEEN THE LOWER ROLL CHOCK AND THE BOTTOM OF THE WINDOW AND YIELDINGLY URGING THE LOWER CHOCKS UPWARDLY, RIGID MEANS EXTENDING IN LOAD TRANSMITTING RELATIONSHIP BETWEEN THE LOWER CHOCK AND THE TOP OF THE WINDOW, AN UPPER ROLL CHOCK SLIDABLY POSITIONED WITHIN THE WINDOW INTERMEDIATE THE LOWER ROLL CHOCK AND THE TOP OF THE WINDOW, RIGID MEANS EXTENDING BETWEEN THE UPPER ROLL CHOCK AND THE TOP OF THE WINDOW, AND UPPER ROLL MEANS AND LOWER ROLL MEANS EXTENDING BETWEEN THE UPPER ROLL CHOCK AND THE TOP OF THE WINDOW, SPECTIVELY IN SAID HOUSINGS. 